1. Field
This disclosure is directed to nanocrystal-metal oxide composites and a method for preparing the composites. More specifically, the nanocrystal-metal oxide composites comprise nanocrystals and a metal oxide bound to the nanocrystals wherein the metal oxide has organic groups.
2. Description of the Related Art
In general, the luminescence and electrical properties of nanocrystals can be controlled by varying various factors (e.g., size and composition) of the nanocrystals. Such characteristics make nanocrystals excellent candidates for application in light-emitting devices, solar cells, sensors, memory devices, and the like.
Nanocrystals may be dispersed in a transparent metal oxide matrix to prepare composites. Use of nanocrystal composites can prevent the constituent nanocrystals from being oxidized or from aggregating due to external stimuli, thereby enhancing the stability of the nanocrystals.
The surface of a nanocrystal prepared by a wet process is covered by an organic dispersant. Before a mixture of such nanocrystals and a metal oxide matrix precursor can undergo a sol-gel reaction to prepare nanocrystal-metal oxide composites, the organic dispersant is replaced with a surfactant having reactivity toward the metal oxide precursor.
The addition of a catalyst and water to the mixture induces crosslinking between the nanocrystals and the metal oxide precursor to form alcohol, water, halogen, or the like, which can cause considerable shrinkage in the volume of the resulting composites.
This volume shrinkage acts to apply mechanical stress to the composites, which can leave defects such as cracks and pores within the composites. Such defects become factors that can cause deterioration of the stability and processability of the composites.